As said above, the first thing to check is the motherboard (chipset, storage controller, NIC(s)) for compatibility. If you run an unsupported storage controller you won't be able to install ESXi as it won't find the (local) disk/SSD.
Same applies to the (onboard) NICs, if ESXi doesn't have a driver for the NIC it will stop installation.
So it might give you a hard time searching and testing community supported drivers and creating self-made custom installation images.
Also, if this is a production system (and not home-lab, testing or any oher non-company use) you won't get any support from VMWare if you are in trouble.
As the actual config of the Win2k8/.NET is on physical hardware it might "perform fine" but with VMWare the physical hardware will be shared and if you run it on minimum requirements (especially for the CPU/cores and amount of RAM) you might face performance issues sooener or later. It's simply because you add the hypevisor level to your virtual servers.